Mygekko api http request

I’m brand new to Home Assistant and need a little hint. I have a mygekko “smarthome” - its very not smart… but I can only control the temperature and shutters over it. the have an api you get the infos like that:

{
	"name":	"HAR",
	"sumstate":	{
		"value":	"State[-2=Hold_down|-1=Down|0=Stop|1=Up|2=Hold_up];Position[%];Angle[°];SumState[0=Ok|1=ManualOff|2=ManualOn|3=Locked|4=Alarm];SlatRotationArea[°]",
		"type":	"STRING",
		"permission":	"READ",
		"index":	200100
	},
	"scmd":	{
		"value":	"-2|-1|0|1|2|T|P55.4|S32.4 (Hold_down|Down|Stop|Up|Hold_up|Toggle|Position|Angle)",
		"type":	"STRING",
		"permission":	"WRITE",
		"index":	200101
	}
}

but you only can shut the shutter down with http get like

GET:http://IP-ADRESS/api/v1/var/blinds/item2/scmd/set?value=-1&username=admin&password=PASSWORD

or you can say that it shut down to 77 % with

GET:http://IP-ADRESS/api/v1/var/blinds/item2/scmd/set?value=P77&username=admin&password=PASSWORD

do you have an hint how I can integrate it in ha ? especially the with a http request where you have a slider convert it to a dynamic url.

Take a look at the rest integration and template cover.